/*
 * ====================================================================
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 *
 */

package com.feilong.lib.org.apache.http.impl;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.InetAddress;
import java.net.Socket;
import java.net.SocketAddress;
import java.net.SocketException;
import java.net.SocketTimeoutException;
import java.nio.charset.CharsetDecoder;
import java.nio.charset.CharsetEncoder;
import java.util.concurrent.atomic.AtomicReference;

import com.feilong.lib.org.apache.http.ConnectionClosedException;
import com.feilong.lib.org.apache.http.Header;
import com.feilong.lib.org.apache.http.HttpConnectionMetrics;
import com.feilong.lib.org.apache.http.HttpEntity;
import com.feilong.lib.org.apache.http.HttpException;
import com.feilong.lib.org.apache.http.HttpInetConnection;
import com.feilong.lib.org.apache.http.HttpMessage;
import com.feilong.lib.org.apache.http.config.MessageConstraints;
import com.feilong.lib.org.apache.http.entity.BasicHttpEntity;
import com.feilong.lib.org.apache.http.entity.ContentLengthStrategy;
import com.feilong.lib.org.apache.http.impl.entity.LaxContentLengthStrategy;
import com.feilong.lib.org.apache.http.impl.entity.StrictContentLengthStrategy;
import com.feilong.lib.org.apache.http.impl.io.ChunkedInputStream;
import com.feilong.lib.org.apache.http.impl.io.ChunkedOutputStream;
import com.feilong.lib.org.apache.http.impl.io.ContentLengthInputStream;
import com.feilong.lib.org.apache.http.impl.io.ContentLengthOutputStream;
import com.feilong.lib.org.apache.http.impl.io.EmptyInputStream;
import com.feilong.lib.org.apache.http.impl.io.HttpTransportMetricsImpl;
import com.feilong.lib.org.apache.http.impl.io.IdentityInputStream;
import com.feilong.lib.org.apache.http.impl.io.IdentityOutputStream;
import com.feilong.lib.org.apache.http.impl.io.SessionInputBufferImpl;
import com.feilong.lib.org.apache.http.impl.io.SessionOutputBufferImpl;
import com.feilong.lib.org.apache.http.io.SessionInputBuffer;
import com.feilong.lib.org.apache.http.io.SessionOutputBuffer;
import com.feilong.lib.org.apache.http.protocol.HTTP;
import com.feilong.lib.org.apache.http.util.Args;
import com.feilong.lib.org.apache.http.util.NetUtils;

/**
 * This class serves as a base for all {@link com.feilong.lib.org.apache.http.HttpConnection} implementations
 * and provides functionality common to both client and server HTTP connections.
 *
 * @since 4.0
 */
public class BHttpConnectionBase implements HttpInetConnection{

    private final SessionInputBufferImpl    inBuffer;

    private final SessionOutputBufferImpl   outbuffer;

    private final MessageConstraints        messageConstraints;

    private final HttpConnectionMetricsImpl connMetrics;

    private final ContentLengthStrategy     incomingContentStrategy;

    private final ContentLengthStrategy     outgoingContentStrategy;

    private final AtomicReference<Socket>   socketHolder;

    /**
     * Creates new instance of BHttpConnectionBase.
     *
     * @param bufferSize
     *            buffer size. Must be a positive number.
     * @param fragmentSizeHint
     *            fragment size hint.
     * @param charDecoder
     *            decoder to be used for decoding HTTP protocol elements.
     *            If {@code null} simple type cast will be used for byte to char conversion.
     * @param charEncoder
     *            encoder to be used for encoding HTTP protocol elements.
     *            If {@code null} simple type cast will be used for char to byte conversion.
     * @param messageConstraints
     *            Message constraints. If {@code null}
     *            {@link MessageConstraints#DEFAULT} will be used.
     * @param incomingContentStrategy
     *            incoming content length strategy. If {@code null}
     *            {@link LaxContentLengthStrategy#INSTANCE} will be used.
     * @param outgoingContentStrategy
     *            outgoing content length strategy. If {@code null}
     *            {@link StrictContentLengthStrategy#INSTANCE} will be used.
     */
    protected BHttpConnectionBase(final int bufferSize, final int fragmentSizeHint, final CharsetDecoder charDecoder,
                    final CharsetEncoder charEncoder, final MessageConstraints messageConstraints,
                    final ContentLengthStrategy incomingContentStrategy, final ContentLengthStrategy outgoingContentStrategy){
        super();
        Args.positive(bufferSize, "Buffer size");
        final HttpTransportMetricsImpl inTransportMetrics = new HttpTransportMetricsImpl();
        final HttpTransportMetricsImpl outTransportMetrics = new HttpTransportMetricsImpl();
        this.inBuffer = new SessionInputBufferImpl(
                        inTransportMetrics,
                        bufferSize,
                        -1,
                        messageConstraints != null ? messageConstraints : MessageConstraints.DEFAULT,
                        charDecoder);
        this.outbuffer = new SessionOutputBufferImpl(outTransportMetrics, bufferSize, fragmentSizeHint, charEncoder);
        this.messageConstraints = messageConstraints;
        this.connMetrics = new HttpConnectionMetricsImpl(inTransportMetrics, outTransportMetrics);
        this.incomingContentStrategy = incomingContentStrategy != null ? incomingContentStrategy : LaxContentLengthStrategy.INSTANCE;
        this.outgoingContentStrategy = outgoingContentStrategy != null ? outgoingContentStrategy : StrictContentLengthStrategy.INSTANCE;
        this.socketHolder = new AtomicReference<>();
    }

    protected void ensureOpen() throws IOException{
        final Socket socket = this.socketHolder.get();
        if (socket == null){
            throw new ConnectionClosedException();
        }
        if (!this.inBuffer.isBound()){
            this.inBuffer.bind(getSocketInputStream(socket));
        }
        if (!this.outbuffer.isBound()){
            this.outbuffer.bind(getSocketOutputStream(socket));
        }
    }

    protected InputStream getSocketInputStream(final Socket socket) throws IOException{
        return socket.getInputStream();
    }

    protected OutputStream getSocketOutputStream(final Socket socket) throws IOException{
        return socket.getOutputStream();
    }

    /**
     * Binds this connection to the given {@link Socket}. This socket will be
     * used by the connection to send and receive data.
     * <p>
     * After this method's execution the connection status will be reported
     * as open and the {@link #isOpen()} will return {@code true}.
     *
     * @param socket
     *            the socket.
     * @throws IOException
     *             in case of an I/O error.
     */
    protected void bind(final Socket socket) throws IOException{
        Args.notNull(socket, "Socket");
        this.socketHolder.set(socket);
        this.inBuffer.bind(null);
        this.outbuffer.bind(null);
    }

    protected SessionInputBuffer getSessionInputBuffer(){
        return this.inBuffer;
    }

    protected SessionOutputBuffer getSessionOutputBuffer(){
        return this.outbuffer;
    }

    protected void doFlush() throws IOException{
        this.outbuffer.flush();
    }

    @Override
    public boolean isOpen(){
        return this.socketHolder.get() != null;
    }

    protected Socket getSocket(){
        return this.socketHolder.get();
    }

    protected OutputStream createOutputStream(final long len,final SessionOutputBuffer outbuffer){
        if (len == ContentLengthStrategy.CHUNKED){
            return new ChunkedOutputStream(2048, outbuffer);
        }else if (len == ContentLengthStrategy.IDENTITY){
            return new IdentityOutputStream(outbuffer);
        }else{
            return new ContentLengthOutputStream(outbuffer, len);
        }
    }

    protected OutputStream prepareOutput(final HttpMessage message) throws HttpException{
        final long len = this.outgoingContentStrategy.determineLength(message);
        return createOutputStream(len, this.outbuffer);
    }

    protected InputStream createInputStream(final long len,final SessionInputBuffer inBuffer){
        if (len == ContentLengthStrategy.CHUNKED){
            return new ChunkedInputStream(inBuffer, this.messageConstraints);
        }else if (len == ContentLengthStrategy.IDENTITY){
            return new IdentityInputStream(inBuffer);
        }else if (len == 0L){
            return EmptyInputStream.INSTANCE;
        }else{
            return new ContentLengthInputStream(inBuffer, len);
        }
    }

    protected HttpEntity prepareInput(final HttpMessage message) throws HttpException{
        final BasicHttpEntity entity = new BasicHttpEntity();

        final long len = this.incomingContentStrategy.determineLength(message);
        final InputStream inStream = createInputStream(len, this.inBuffer);
        if (len == ContentLengthStrategy.CHUNKED){
            entity.setChunked(true);
            entity.setContentLength(-1);
            entity.setContent(inStream);
        }else if (len == ContentLengthStrategy.IDENTITY){
            entity.setChunked(false);
            entity.setContentLength(-1);
            entity.setContent(inStream);
        }else{
            entity.setChunked(false);
            entity.setContentLength(len);
            entity.setContent(inStream);
        }

        final Header contentTypeHeader = message.getFirstHeader(HTTP.CONTENT_TYPE);
        if (contentTypeHeader != null){
            entity.setContentType(contentTypeHeader);
        }
        final Header contentEncodingHeader = message.getFirstHeader(HTTP.CONTENT_ENCODING);
        if (contentEncodingHeader != null){
            entity.setContentEncoding(contentEncodingHeader);
        }
        return entity;
    }

    @Override
    public InetAddress getLocalAddress(){
        final Socket socket = this.socketHolder.get();
        return socket != null ? socket.getLocalAddress() : null;
    }

    @Override
    public int getLocalPort(){
        final Socket socket = this.socketHolder.get();
        return socket != null ? socket.getLocalPort() : -1;
    }

    @Override
    public InetAddress getRemoteAddress(){
        final Socket socket = this.socketHolder.get();
        return socket != null ? socket.getInetAddress() : null;
    }

    @Override
    public int getRemotePort(){
        final Socket socket = this.socketHolder.get();
        return socket != null ? socket.getPort() : -1;
    }

    @Override
    public void setSocketTimeout(final int timeout){
        final Socket socket = this.socketHolder.get();
        if (socket != null){
            try{
                socket.setSoTimeout(timeout);
            }catch (final SocketException ignore){
                // It is not quite clear from the Sun's documentation if there are any
                // other legitimate cases for a socket exception to be thrown when setting
                // SO_TIMEOUT besides the socket being already closed
            }
        }
    }

    @Override
    public int getSocketTimeout(){
        final Socket socket = this.socketHolder.get();
        if (socket != null){
            try{
                return socket.getSoTimeout();
            }catch (final SocketException ignore){
                // ignore
            }
        }
        return -1;
    }

    @Override
    public void shutdown() throws IOException{
        final Socket socket = this.socketHolder.getAndSet(null);
        if (socket != null){
            // force abortive close (RST)
            try{
                socket.setSoLinger(true, 0);
            }catch (final IOException ex){}finally{
                socket.close();
            }
        }
    }

    @Override
    public void close() throws IOException{
        final Socket socket = this.socketHolder.getAndSet(null);
        if (socket != null){
            try{
                this.inBuffer.clear();
                this.outbuffer.flush();
            }finally{
                socket.close();
            }
        }
    }

    private int fillInputBuffer(final int timeout) throws IOException{
        final Socket socket = this.socketHolder.get();
        final int oldtimeout = socket.getSoTimeout();
        try{
            socket.setSoTimeout(timeout);
            return this.inBuffer.fillBuffer();
        }finally{
            socket.setSoTimeout(oldtimeout);
        }
    }

    protected boolean awaitInput(final int timeout) throws IOException{
        if (this.inBuffer.hasBufferedData()){
            return true;
        }
        fillInputBuffer(timeout);
        return this.inBuffer.hasBufferedData();
    }

    @Override
    public boolean isStale(){
        if (!isOpen()){
            return true;
        }
        try{
            final int bytesRead = fillInputBuffer(1);
            return bytesRead < 0;
        }catch (final SocketTimeoutException ex){
            return false;
        }catch (final IOException ex){
            return true;
        }
    }

    protected void incrementRequestCount(){
        this.connMetrics.incrementRequestCount();
    }

    protected void incrementResponseCount(){
        this.connMetrics.incrementResponseCount();
    }

    @Override
    public HttpConnectionMetrics getMetrics(){
        return this.connMetrics;
    }

    @Override
    public String toString(){
        final Socket socket = this.socketHolder.get();
        if (socket != null){
            final StringBuilder buffer = new StringBuilder();
            final SocketAddress remoteAddress = socket.getRemoteSocketAddress();
            final SocketAddress localAddress = socket.getLocalSocketAddress();
            if (remoteAddress != null && localAddress != null){
                NetUtils.formatAddress(buffer, localAddress);
                buffer.append("<->");
                NetUtils.formatAddress(buffer, remoteAddress);
            }
            return buffer.toString();
        }
        return "[Not bound]";
    }

}
